Active noise cancellation (ANC) technology is based on the wave superposition principle, which generates the waveform opposite to the waveform of noise and actively reduces acoustic noise in the air. Generally, the ANC technology detects a noise reference signal from the outside using one or more microphones, generates a signal having a waveform of which a phase is shifted by 180 degrees from the noise reference signal, and reproduces the same through one or more speakers. Accordingly, the waveform of the original noise reference signal and the waveform of which the phase is shifted by 180 degrees may experience destructive interference, and thus, noise arriving at the ears of a user may be reduced.
An active noise cancellation (ANC) circuit may be applied to recent portable electronic devices (for example, an electronic device that is used for listening sound in noisy environments, such as a portable phone, a smart phone, a music player, ear phones, a headphone, and the like), and thus, noise from the surroundings may be reduced. The ANC circuit may be mounted on, for example, a headphone, and may reduce external noise by reproducing noise collected by a microphone from the surroundings as a signal in a waveform of which a phase is shifted by 180 degrees. However, when vibrations are applied to the headphone itself or abnormally excessive input is generated, unintended noise may occur. This may cause the ANC circuit to detect a noise signal that actually does not exist in the audible frequency or a distorted noise signal due to a physical vibration or abnormal input in a microphone. When the ANC circuit reproduces the same as a signal in a phase shifted waveform, noise that does not actually exist in the audible frequency may be generated and displeasure and audio shock may be delivered to a user.
Therefore, a need exists for a method of stably cancelling noise and an electronic device thereof, which may prevent noise from being generated by a physical vibration or abnormal input that is not connected with acoustic noise in the air, in the electronic device to which the ANC technology is applied.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.